1. Field of the Invention
The present invention relates to an apparatus for performing sequence control of electronic equipment.
2. Description of the Prior Art
Recently, one-chip microcomputers have been developed having a wide application, such as in industrial equipment, commercial equipment, and the like. Since they have greatly reduced cost, one-chip microcomputers have become essential to sequence controllers. Furthermore, performance has recently been improved and cost lowered by expanding memory capacity, extending an I/O port, and integrating functions of a counter, A/DC, D/AC, PLL, CCD drivers and the like on one chip. However, development of products to which high performance microcomputers can be applied has lagged behind the development of microcomputers. This is because it takes a long time to develop a product to which the microcomputer is applied, and the program development thereof requires many steps. This is a serious problem when keen competition demands that products be continually improved.
Generally, the number of steps required for programming exponentially increases with required improvements in functions, requiring many engineers. The number of days required for product development depends upon the number of steps required for programming. This greatly affects profitability. FIG. 1 shows the relationship between a program capacity and the number of months required for programming (including debugging). As can be seen from this graph, programming requires many months.
Thus, every time a new product is developed, the time required for developing software is increased and interferes with product development, as has been described above. Although performance of the equipment can be improved using microcomputers, their use causes an increase in the number of steps needed for development.
As an example, in the case of electronic copy machines, product development is generally started when specific processes of the copy machine (e.g., a photosensitive member, toner, paper, and a matching characteristic therewith) are unstable. Since a microcomputer system is developed parallel to the stabilization of such processes, an alteration in design including software and hardware must be performed twice or more depending upon a state of the processes, Thus, the programming and debugging must be started from the beginning for each design alteration, and the number of steps is further increased. This delays product development, and increases the work load for programmers.
Conventionally, software and hardware are developed specifically for each product. Therefore, when a new product is developed, software and hardware must again be designed for that product. When a new chip is introduced, development tools must be prepared and personnel must be trained. This also increases the number of steps required for development.
Therefore, sequence control programs of a copy machine are usually monitored and stored in memories, and respective programs are divided into tasks so as to form corresponding modules. Thus, programs need not be developed every time the machine is redesigned, and desired programs are constituted using library standard module programs. With this method, since the programs need not be completely redeveloped, development time can be shortened. However, a program capacity is greatly increased, and particularly in machines such as a copy machine, an OCR, an intelligent robot and the like which must be operated in real time, real time control of tasks cannot be performed, Furthermore, in the von Neumann method wherein a sequence is advanced step-by-step by collating with programs, a program flow is complex, processing speed is low, and analog processing cannot be performed.